Sink



FIG. 1 is a front perspective view of a sink showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a right side elevational view thereof, the left side being a mirror image. 

The ornamental design for a sink, as shown and described. 